Generally, cryogenic liquid refers to a material cooled and liquefied to several or tens of kelvins (K) or less, such as liquid helium (LHe), liquid nitrogen, liquid oxygen, and liquid hydrogen.
Recently, demands for cryogenic liquid are increasing in various high-tech fields such as next-generation semiconductor manufacturing technologies. In particular, helium is widely used in film deposition or the like in advanced processes for coping with a decrease in size of the geometric structure of the integrated circuits in progressive semiconductor manufacturing process.
Accordingly, as demands for cryogenic liquid such as liquid helium increase, there are suggested various methods for providing cryogenic liquid to, for example, a semiconductor manufacturing factory that is not capable of self-producing cryogenic liquid have been attempted. Among these methods, there is a method to provide cryogenic liquid through transfer lines to a number of target companies at remote places.
Meanwhile, since cryogenic liquid may be easily vaporized if it is transferred through a transfer line exposed to external heat such as radiant heat, it is highly important to insulate a transfer line through which cryogenic liquid is transferred.
To that end, various transfer lines for avoiding loss of the cryogenic liquid by external heat are suggested. The suggested transfer lines, however, may entail a loss of cryogenic liquid by radiant heat in a long distance transfer, have complex structures, and have difficulty in reducing a heat transmission rate due to adhesion effect between insulation films that surround a transfer line.
As such, there has been a growing demand for a transfer line with an improved structure that can solve the aforementioned problems, be more readily manufactured, and more efficiently block heat from the outside.